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+<?xml version='1.0' encoding='UTF-8'?>
+<?xml-stylesheet type="text/xsl"
+ href="http://docbook.sourceforge.net/release/xsl/current/manpages/docbook.xsl"?>
+<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.4//EN"
+ "http://www.oasis-open.org/docbook/xml/4.4/docbookx.dtd" [
+]>
+
+<refentry>
+ <refentryinfo>
+ <title>User Manual</title>
+ <productname>jemalloc</productname>
+ <releaseinfo role="version">@jemalloc_version@</releaseinfo>
+ <authorgroup>
+ <author>
+ <firstname>Jason</firstname>
+ <surname>Evans</surname>
+ <personblurb>Author</personblurb>
+ </author>
+ </authorgroup>
+ </refentryinfo>
+ <refmeta>
+ <refentrytitle>JEMALLOC</refentrytitle>
+ <manvolnum>3</manvolnum>
+ </refmeta>
+ <refnamediv>
+ <refdescriptor>jemalloc</refdescriptor>
+ <refname>jemalloc</refname>
+ <!-- Each refname causes a man page file to be created. Only if this were
+ the system malloc(3) implementation would these files be appropriate.
+ <refname>malloc</refname>
+ <refname>calloc</refname>
+ <refname>posix_memalign</refname>
+ <refname>realloc</refname>
+ <refname>free</refname>
+ <refname>malloc_usable_size</refname>
+ <refname>malloc_stats_print</refname>
+ <refname>mallctl</refname>
+ <refname>mallctlnametomib</refname>
+ <refname>mallctlbymib</refname>
+ <refname>allocm</refname>
+ <refname>rallocm</refname>
+ <refname>sallocm</refname>
+ <refname>dallocm</refname>
+ -->
+ <refpurpose>general purpose memory allocation functions</refpurpose>
+ </refnamediv>
+ <refsect1 id="library">
+ <title>LIBRARY</title>
+ <para>This manual describes jemalloc @jemalloc_version@. More information
+ can be found at the <ulink
+ url="http://www.canonware.com/jemalloc/">jemalloc website</ulink>.</para>
+ </refsect1>
+ <refsynopsisdiv>
+ <title>SYNOPSIS</title>
+ <funcsynopsis>
+ <funcsynopsisinfo>#include <<filename class="headerfile">stdlib.h</filename>>
+#include <<filename class="headerfile">jemalloc/jemalloc.h</filename>></funcsynopsisinfo>
+ <refsect2>
+ <title>Standard API</title>
+ <funcprototype>
+ <funcdef>void *<function>malloc</function></funcdef>
+ <paramdef>size_t <parameter>size</parameter></paramdef>
+ </funcprototype>
+ <funcprototype>
+ <funcdef>void *<function>calloc</function></funcdef>
+ <paramdef>size_t <parameter>number</parameter></paramdef>
+ <paramdef>size_t <parameter>size</parameter></paramdef>
+ </funcprototype>
+ <funcprototype>
+ <funcdef>int <function>posix_memalign</function></funcdef>
+ <paramdef>void **<parameter>ptr</parameter></paramdef>
+ <paramdef>size_t <parameter>alignment</parameter></paramdef>
+ <paramdef>size_t <parameter>size</parameter></paramdef>
+ </funcprototype>
+ <funcprototype>
+ <funcdef>void *<function>realloc</function></funcdef>
+ <paramdef>void *<parameter>ptr</parameter></paramdef>
+ <paramdef>size_t <parameter>size</parameter></paramdef>
+ </funcprototype>
+ <funcprototype>
+ <funcdef>void <function>free</function></funcdef>
+ <paramdef>void *<parameter>ptr</parameter></paramdef>
+ </funcprototype>
+ </refsect2>
+ <refsect2>
+ <title>Non-standard API</title>
+ <funcprototype>
+ <funcdef>size_t <function>malloc_usable_size</function></funcdef>
+ <paramdef>const void *<parameter>ptr</parameter></paramdef>
+ </funcprototype>
+ <funcprototype>
+ <funcdef>void <function>malloc_stats_print</function></funcdef>
+ <paramdef>void <parameter>(*write_cb)</parameter>
+ <funcparams>void *, const char *</funcparams>
+ </paramdef>
+ <paramdef>void *<parameter>cbopaque</parameter></paramdef>
+ <paramdef>const char *<parameter>opts</parameter></paramdef>
+ </funcprototype>
+ <funcprototype>
+ <funcdef>int <function>mallctl</function></funcdef>
+ <paramdef>const char *<parameter>name</parameter></paramdef>
+ <paramdef>void *<parameter>oldp</parameter></paramdef>
+ <paramdef>size_t *<parameter>oldlenp</parameter></paramdef>
+ <paramdef>void *<parameter>newp</parameter></paramdef>
+ <paramdef>size_t <parameter>newlen</parameter></paramdef>
+ </funcprototype>
+ <funcprototype>
+ <funcdef>int <function>mallctlnametomib</function></funcdef>
+ <paramdef>const char *<parameter>name</parameter></paramdef>
+ <paramdef>size_t *<parameter>mibp</parameter></paramdef>
+ <paramdef>size_t *<parameter>miblenp</parameter></paramdef>
+ </funcprototype>
+ <funcprototype>
+ <funcdef>int <function>mallctlbymib</function></funcdef>
+ <paramdef>const size_t *<parameter>mib</parameter></paramdef>
+ <paramdef>size_t <parameter>miblen</parameter></paramdef>
+ <paramdef>void *<parameter>oldp</parameter></paramdef>
+ <paramdef>size_t *<parameter>oldlenp</parameter></paramdef>
+ <paramdef>void *<parameter>newp</parameter></paramdef>
+ <paramdef>size_t <parameter>newlen</parameter></paramdef>
+ </funcprototype>
+ <funcprototype>
+ <funcdef>void <function>(*malloc_message)</function></funcdef>
+ <paramdef>void *<parameter>cbopaque</parameter></paramdef>
+ <paramdef>const char *<parameter>s</parameter></paramdef>
+ </funcprototype>
+ <para><type>const char *</type><varname>malloc_conf</varname>;</para>
+ </refsect2>
+ <refsect2>
+ <title>Experimental API</title>
+ <funcprototype>
+ <funcdef>int <function>allocm</function></funcdef>
+ <paramdef>void **<parameter>ptr</parameter></paramdef>
+ <paramdef>size_t *<parameter>rsize</parameter></paramdef>
+ <paramdef>size_t <parameter>size</parameter></paramdef>
+ <paramdef>int <parameter>flags</parameter></paramdef>
+ </funcprototype>
+ <funcprototype>
+ <funcdef>int <function>rallocm</function></funcdef>
+ <paramdef>void **<parameter>ptr</parameter></paramdef>
+ <paramdef>size_t *<parameter>rsize</parameter></paramdef>
+ <paramdef>size_t <parameter>size</parameter></paramdef>
+ <paramdef>size_t <parameter>extra</parameter></paramdef>
+ <paramdef>int <parameter>flags</parameter></paramdef>
+ </funcprototype>
+ <funcprototype>
+ <funcdef>int <function>sallocm</function></funcdef>
+ <paramdef>const void *<parameter>ptr</parameter></paramdef>
+ <paramdef>size_t *<parameter>rsize</parameter></paramdef>
+ <paramdef>int <parameter>flags</parameter></paramdef>
+ </funcprototype>
+ <funcprototype>
+ <funcdef>int <function>dallocm</function></funcdef>
+ <paramdef>void *<parameter>ptr</parameter></paramdef>
+ <paramdef>int <parameter>flags</parameter></paramdef>
+ </funcprototype>
+ </refsect2>
+ </funcsynopsis>
+ </refsynopsisdiv>
+ <refsect1 id="description">
+ <title>DESCRIPTION</title>
+ <refsect2>
+ <title>Standard API</title>
+
+ <para>The <function>malloc<parameter/></function> function allocates
+ <parameter>size</parameter> bytes of uninitialized memory. The allocated
+ space is suitably aligned (after possible pointer coercion) for storage
+ of any type of object.</para>
+
+ <para>The <function>calloc<parameter/></function> function allocates
+ space for <parameter>number</parameter> objects, each
+ <parameter>size</parameter> bytes in length. The result is identical to
+ calling <function>malloc<parameter/></function> with an argument of
+ <parameter>number</parameter> * <parameter>size</parameter>, with the
+ exception that the allocated memory is explicitly initialized to zero
+ bytes.</para>
+
+ <para>The <function>posix_memalign<parameter/></function> function
+ allocates <parameter>size</parameter> bytes of memory such that the
+ allocation's base address is an even multiple of
+ <parameter>alignment</parameter>, and returns the allocation in the value
+ pointed to by <parameter>ptr</parameter>. The requested
+ <parameter>alignment</parameter> must be a power of 2 at least as large
+ as <code language="C">sizeof(<type>void *</type>)</code>.</para>
+
+ <para>The <function>realloc<parameter/></function> function changes the
+ size of the previously allocated memory referenced by
+ <parameter>ptr</parameter> to <parameter>size</parameter> bytes. The
+ contents of the memory are unchanged up to the lesser of the new and old
+ sizes. If the new size is larger, the contents of the newly allocated
+ portion of the memory are undefined. Upon success, the memory referenced
+ by <parameter>ptr</parameter> is freed and a pointer to the newly
+ allocated memory is returned. Note that
+ <function>realloc<parameter/></function> may move the memory allocation,
+ resulting in a different return value than <parameter>ptr</parameter>.
+ If <parameter>ptr</parameter> is <constant>NULL</constant>, the
+ <function>realloc<parameter/></function> function behaves identically to
+ <function>malloc<parameter/></function> for the specified size.</para>
+
+ <para>The <function>free<parameter/></function> function causes the
+ allocated memory referenced by <parameter>ptr</parameter> to be made
+ available for future allocations. If <parameter>ptr</parameter> is
+ <constant>NULL</constant>, no action occurs.</para>
+ </refsect2>
+ <refsect2>
+ <title>Non-standard API</title>
+
+ <para>The <function>malloc_usable_size<parameter/></function> function
+ returns the usable size of the allocation pointed to by
+ <parameter>ptr</parameter>. The return value may be larger than the size
+ that was requested during allocation. The
+ <function>malloc_usable_size<parameter/></function> function is not a
+ mechanism for in-place <function>realloc<parameter/></function>; rather
+ it is provided solely as a tool for introspection purposes. Any
+ discrepancy between the requested allocation size and the size reported
+ by <function>malloc_usable_size<parameter/></function> should not be
+ depended on, since such behavior is entirely implementation-dependent.
+ </para>
+
+ <para>The <function>malloc_stats_print<parameter/></function> function
+ writes human-readable summary statistics via the
+ <parameter>write_cb</parameter> callback function pointer and
+ <parameter>cbopaque</parameter> data passed to
+ <parameter>write_cb</parameter>, or
+ <function>malloc_message<parameter/></function> if
+ <parameter>write_cb</parameter> is <constant>NULL</constant>. This
+ function can be called repeatedly. General information that never
+ changes during execution can be omitted by specifying "g" as a character
+ within the <parameter>opts</parameter> string. Note that
+ <function>malloc_message<parameter/></function> uses the
+ <function>mallctl*<parameter/></function> functions internally, so
+ inconsistent statistics can be reported if multiple threads use these
+ functions simultaneously. If <option>--enable-stats</option> is
+ specified during configuration, “m” and “a” can
+ be specified to omit merged arena and per arena statistics, respectively;
+ “b” and “l” can be specified to omit per size
+ class statistics for bins and large objects, respectively. Unrecognized
+ characters are silently ignored. Note that thread caching may prevent
+ some statistics from being completely up to date, since extra locking
+ would be required to merge counters that track thread cache operations.
+ </para>
+
+ <para>The <function>mallctl<parameter/></function> function provides a
+ general interface for introspecting the memory allocator, as well as
+ setting modifiable parameters and triggering actions. The
+ period-separated <parameter>name</parameter> argument specifies a
+ location in a tree-structured namespace; see the <xref
+ linkend="mallctl_namespace" xrefstyle="template:%t"/> section for
+ documentation on the tree contents. To read a value, pass a pointer via
+ <parameter>oldp</parameter> to adequate space to contain the value, and a
+ pointer to its length via <parameter>oldlenp</parameter>; otherwise pass
+ <constant>NULL</constant> and <constant>NULL</constant>. Similarly, to
+ write a value, pass a pointer to the value via
+ <parameter>newp</parameter>, and its length via
+ <parameter>newlen</parameter>; otherwise pass <constant>NULL</constant>
+ and <constant>0</constant>.</para>
+
+ <para>The <function>mallctlnametomib<parameter/></function> function
+ provides a way to avoid repeated name lookups for applications that
+ repeatedly query the same portion of the namespace, by translating a name
+ to a “Management Information Base” (MIB) that can be passed
+ repeatedly to <function>mallctlbymib<parameter/></function>. Upon
+ successful return from <function>mallctlnametomib<parameter/></function>,
+ <parameter>mibp</parameter> contains an array of
+ <parameter>*miblenp</parameter> integers, where
+ <parameter>*miblenp</parameter> is the lesser of the number of components
+ in <parameter>name</parameter> and the input value of
+ <parameter>*miblenp</parameter>. Thus it is possible to pass a
+ <parameter>*miblenp</parameter> that is smaller than the number of
+ period-separated name components, which results in a partial MIB that can
+ be used as the basis for constructing a complete MIB. For name
+ components that are integers (e.g. the 2 in
+ <link
+ linkend="arenas.bin.i.size"><mallctl>arenas.bin.2.size</mallctl></link>),
+ the corresponding MIB component will always be that integer. Therefore,
+ it is legitimate to construct code like the following: <programlisting
+ language="C"><![CDATA[
+unsigned nbins, i;
+
+int mib[4];
+size_t len, miblen;
+
+len = sizeof(nbins);
+mallctl("arenas.nbins", &nbins, &len, NULL, 0);
+
+miblen = 4;
+mallnametomib("arenas.bin.0.size", mib, &miblen);
+for (i = 0; i < nbins; i++) {
+ size_t bin_size;
+
+ mib[2] = i;
+ len = sizeof(bin_size);
+ mallctlbymib(mib, miblen, &bin_size, &len, NULL, 0);
+ /* Do something with bin_size... */
+}]]></programlisting></para>
+ </refsect2>
+ <refsect2>
+ <title>Experimental API</title>
+ <para>The experimental API is subject to change or removal without regard
+ for backward compatibility.</para>
+
+ <para>The <function>allocm<parameter/></function>,
+ <function>rallocm<parameter/></function>,
+ <function>sallocm<parameter/></function>, and
+ <function>dallocm<parameter/></function> functions all have a
+ <parameter>flags</parameter> argument that can be used to specify
+ options. The functions only check the options that are contextually
+ relevant. Use bitwise or (<code language="C">|</code>) operations to
+ specify one or more of the following:
+ <variablelist>
+ <varlistentry>
+ <term><constant>ALLOCM_LG_ALIGN(<parameter>la</parameter>)
+ </constant></term>
+
+ <listitem><para>Align the memory allocation to start at an address
+ that is a multiple of <code language="C">(1 <<
+ <parameter>la</parameter>)</code>. This macro does not validate
+ that <parameter>la</parameter> is within the valid
+ range.</para></listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><constant>ALLOCM_ALIGN(<parameter>a</parameter>)
+ </constant></term>
+
+ <listitem><para>Align the memory allocation to start at an address
+ that is a multiple of <parameter>a</parameter>, where
+ <parameter>a</parameter> is a power of two. This macro does not
+ validate that <parameter>a</parameter> is a power of 2.
+ </para></listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><constant>ALLOCM_ZERO</constant></term>
+
+ <listitem><para>Initialize newly allocated memory to contain zero
+ bytes. In the growing reallocation case, the real size prior to
+ reallocation defines the boundary between untouched bytes and those
+ that are initialized to contain zero bytes. If this option is
+ absent, newly allocated memory is uninitialized.</para></listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><constant>ALLOCM_NO_MOVE</constant></term>
+
+ <listitem><para>For reallocation, fail rather than moving the
+ object. This constraint can apply to both growth and
+ shrinkage.</para></listitem>
+ </varlistentry>
+ </variablelist>
+ </para>
+
+ <para>The <function>allocm<parameter/></function> function allocates at
+ least <parameter>size</parameter> bytes of memory, sets
+ <parameter>*ptr</parameter> to the base address of the allocation, and
+ sets <parameter>*rsize</parameter> to the real size of the allocation if
+ <parameter>rsize</parameter> is not <constant>NULL</constant>.</para>
+
+ <para>The <function>rallocm<parameter/></function> function resizes the
+ allocation at <parameter>*ptr</parameter> to be at least
+ <parameter>size</parameter> bytes, sets <parameter>*ptr</parameter> to
+ the base address of the allocation if it moved, and sets
+ <parameter>*rsize</parameter> to the real size of the allocation if
+ <parameter>rsize</parameter> is not <constant>NULL</constant>. If
+ <parameter>extra</parameter> is non-zero, an attempt is made to resize
+ the allocation to be at least <code
+ language="C"><parameter>size</parameter> +
+ <parameter>extra</parameter>)</code> bytes, though inability to allocate
+ the extra byte(s) will not by itself result in failure. Behavior is
+ undefined if <code language="C">(<parameter>size</parameter> +
+ <parameter>extra</parameter> >
+ <constant>SIZE_T_MAX</constant>)</code>.</para>
+
+ <para>The <function>sallocm<parameter/></function> function sets
+ <parameter>*rsize</parameter> to the real size of the allocation.</para>
+
+ <para>The <function>dallocm<parameter/></function> function causes the
+ memory referenced by <parameter>ptr</parameter> to be made available for
+ future allocations.</para>
+ </refsect2>
+ </refsect1>
+ <refsect1 id="tuning">
+ <title>TUNING</title>
+ <para>Once, when the first call is made to one of the memory allocation
+ routines, the allocator initializes its internals based in part on various
+ options that can be specified at compile- or run-time.</para>
+
+ <para>The string pointed to by the global variable
+ <varname>malloc_conf</varname>, the “name” of the file
+ referenced by the symbolic link named <filename
+ class="symlink">/etc/malloc.conf</filename>, and the value of the
+ environment variable <envar>MALLOC_CONF</envar>, will be interpreted, in
+ that order, from left to right as options.</para>
+
+ <para>An options string is a comma-separated list of option:value pairs.
+ There is one key corresponding to each <link
+ linkend="opt.abort"><mallctl>opt.*</mallctl></link> mallctl (see the <xref
+ linkend="mallctl_namespace" xrefstyle="template:%t"/> section for options
+ documentation). For example, <literal>abort:true,narenas:1</literal> sets
+ the <link linkend="opt.abort"><mallctl>opt.abort</mallctl></link> and <link
+ linkend="opt.narenas"><mallctl>opt.narenas</mallctl></link> options. Some
+ options have boolean values (true/false), others have integer values (base
+ 8, 10, or 16, depending on prefix), and yet others have raw string
+ values.</para>
+ </refsect1>
+ <refsect1 id="implementation_notes">
+ <title>IMPLEMENTATION NOTES</title>
+ <para>Traditionally, allocators have used
+ <citerefentry><refentrytitle>sbrk</refentrytitle>
+ <manvolnum>2</manvolnum></citerefentry> to obtain memory, which is
+ suboptimal for several reasons, including race conditions, increased
+ fragmentation, and artificial limitations on maximum usable memory. If
+ <option>--enable-dss</option> is specified during configuration, this
+ allocator uses both <citerefentry><refentrytitle>sbrk</refentrytitle>
+ <manvolnum>2</manvolnum></citerefentry> and
+ <citerefentry><refentrytitle>mmap</refentrytitle>
+ <manvolnum>2</manvolnum></citerefentry>, in that order of preference;
+ otherwise only <citerefentry><refentrytitle>mmap</refentrytitle>
+ <manvolnum>2</manvolnum></citerefentry> is used.</para>
+
+ <para>This allocator uses multiple arenas in order to reduce lock
+ contention for threaded programs on multi-processor systems. This works
+ well with regard to threading scalability, but incurs some costs. There is
+ a small fixed per-arena overhead, and additionally, arenas manage memory
+ completely independently of each other, which means a small fixed increase
+ in overall memory fragmentation. These overheads are not generally an
+ issue, given the number of arenas normally used. Note that using
+ substantially more arenas than the default is not likely to improve
+ performance, mainly due to reduced cache performance. However, it may make
+ sense to reduce the number of arenas if an application does not make much
+ use of the allocation functions.</para>
+
+ <para>In addition to multiple arenas, unless
+ <option>--disable-tcache</option> is specified during configuration, this
+ allocator supports thread-specific caching for small and large objects, in
+ order to make it possible to completely avoid synchronization for most
+ allocation requests. Such caching allows very fast allocation in the
+ common case, but it increases memory usage and fragmentation, since a
+ bounded number of objects can remain allocated in each thread cache.</para>
+
+ <para>Memory is conceptually broken into equal-sized chunks, where the
+ chunk size is a power of two that is greater than the page size. Chunks
+ are always aligned to multiples of the chunk size. This alignment makes it
+ possible to find metadata for user objects very quickly.</para>
+
+ <para>User objects are broken into three categories according to size:
+ small, large, and huge. Small objects are smaller than one page. Large
+ objects are smaller than the chunk size. Huge objects are a multiple of
+ the chunk size. Small and large objects are managed by arenas; huge
+ objects are managed separately in a single data structure that is shared by
+ all threads. Huge objects are used by applications infrequently enough
+ that this single data structure is not a scalability issue.</para>
+
+ <para>Each chunk that is managed by an arena tracks its contents as runs of
+ contiguous pages (unused, backing a set of small objects, or backing one
+ large object). The combination of chunk alignment and chunk page maps
+ makes it possible to determine all metadata regarding small and large
+ allocations in constant time.</para>
+
+ <para>Small objects are managed in groups by page runs. Each run maintains
+ a frontier and free list to track which regions are in use. Unless
+ <option>--disable-tiny</option> is specified during configuration,
+ allocation requests that are no more than half the quantum (8 or 16,
+ depending on architecture) are rounded up to the nearest power of two that
+ is at least <code language="C">sizeof(<type>void *</type>)</code>.
+ Allocation requests that are more than half the quantum, but no more than
+ the minimum cacheline-multiple size class (see the <link
+ linkend="opt.lg_qspace_max"><mallctl>opt.lg_qspace_max</mallctl></link>
+ option) are rounded up to the nearest multiple of the quantum. Allocation
+ requests that are more than the minimum cacheline-multiple size class, but
+ no more than the minimum subpage-multiple size class (see the <link
+ linkend="opt.lg_cspace_max"><mallctl>opt.lg_cspace_max</mallctl></link>
+ option) are rounded up to the nearest multiple of the cacheline size (64).
+ Allocation requests that are more than the minimum subpage-multiple size
+ class, but no more than the maximum subpage-multiple size class are rounded
+ up to the nearest multiple of the subpage size (256). Allocation requests
+ that are more than the maximum subpage-multiple size class, but small
+ enough to fit in an arena-managed chunk (see the <link
+ linkend="opt.lg_chunk"><mallctl>opt.lg_chunk</mallctl></link> option), are
+ rounded up to the nearest run size. Allocation requests that are too large
+ to fit in an arena-managed chunk are rounded up to the nearest multiple of
+ the chunk size.</para>
+
+ <para>Allocations are packed tightly together, which can be an issue for
+ multi-threaded applications. If you need to assure that allocations do not
+ suffer from cacheline sharing, round your allocation requests up to the
+ nearest multiple of the cacheline size, or specify cacheline alignment when
+ allocating.</para>
+
+ <para>Assuming 4 MiB chunks, 4 KiB pages, and a 16-byte quantum on a 64-bit
+ system, the size classes in each category are as shown in <xref
+ linkend="size_classes" xrefstyle="template:Table %n"/>.</para>
+
+ <table xml:id="size_classes" frame="all">
+ <title>Size classes</title>
+ <tgroup cols="3" align="left" colsep="1" rowsep="1">
+ <colspec colname="c1"/>
+ <colspec colname="c2"/>
+ <colspec colname="c3"/>
+ <thead>
+ <row>
+ <entry>Category</entry>
+ <entry>Subcategory</entry>
+ <entry>Size</entry>
+ </row>
+ </thead>
+ <tbody>
+ <row>
+ <entry morerows="3">Small</entry>
+ <entry>Tiny</entry>
+ <entry>[8]</entry>
+ </row>
+ <row>
+ <entry>Quantum-spaced</entry>
+ <entry>[16, 32, 48, ..., 128]</entry>
+ </row>
+ <row>
+ <entry>Cacheline-spaced</entry>
+ <entry>[192, 256, 320, ..., 512]</entry>
+ </row>
+ <row>
+ <entry>Subpage-spaced</entry>
+ <entry>[768, 1024, 1280, ..., 3840]</entry>
+ </row>
+ <row>
+ <entry namest="c1" nameend="c2">Large</entry>
+ <entry>[4 KiB, 8 KiB, 12 KiB, ..., 4072 KiB]</entry>
+ </row>
+ <row>
+ <entry namest="c1" nameend="c2">Huge</entry>
+ <entry>[4 MiB, 8 MiB, 12 MiB, ...]</entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+ </refsect1>
+ <refsect1 id="mallctl_namespace">
+ <title>MALLCTL NAMESPACE</title>
+ <para>The following names are defined in the namespace accessible via the
+ <function>mallctl*<parameter/></function> functions. Value types are
+ specified in parentheses, their readable/writable statuses are encoded as
+ <literal>rw</literal>, <literal>r-</literal>, <literal>-w</literal>, or
+ <literal>--</literal>, and required build configuration flags follow, if
+ any. A name element encoded as <literal><i></literal> or
+ <literal><j></literal> indicates an integer component, where the
+ integer varies from 0 to some upper value that must be determined via
+ introspection. In the case of <mallctl>stats.arenas.<i>.*</mallctl>,
+ <literal><i></literal> equal to <link
+ linkend="arenas.narenas"><mallctl>arenas.narenas</mallctl></link> can be
+ used to access the summation of statistics from all arenas. Take special
+ note of the <link linkend="epoch"><mallctl>epoch</mallctl></link> mallctl,
+ which controls refreshing of cached dynamic statistics.</para>
+
+ <variablelist>
+ <varlistentry>
+ <term>
+ <mallctl>version</mallctl>
+ (<type>const char *</type>)
+ <literal>r-</literal>
+ </term>
+ <listitem><para>Return the jemalloc version string.</para></listitem>
+ </varlistentry>
+
+ <varlistentry id="epoch">
+ <term>
+ <mallctl>epoch</mallctl>
+ (<type>uint64_t</type>)
+ <literal>rw</literal>
+ </term>
+ <listitem><para>If a value is passed in, refresh the data from which
+ the <function>mallctl*<parameter/></function> functions report values,
+ and increment the epoch. Return the current epoch. This is useful for
+ detecting whether another thread caused a refresh.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>
+ <mallctl>config.debug</mallctl>
+ (<type>bool</type>)
+ <literal>r-</literal>
+ </term>
+ <listitem><para><option>--enable-debug</option> was specified during
+ build configuration.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>
+ <mallctl>config.dss</mallctl>
+ (<type>bool</type>)
+ <literal>r-</literal>
+ </term>
+ <listitem><para><option>--enable-dss</option> was specified during
+ build configuration.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>
+ <mallctl>config.dynamic_page_shift</mallctl>
+ (<type>bool</type>)
+ <literal>r-</literal>
+ </term>
+ <listitem><para><option>--enable-dynamic-page-shift</option> was
+ specified during build configuration.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>
+ <mallctl>config.fill</mallctl>
+ (<type>bool</type>)
+ <literal>r-</literal>
+ </term>
+ <listitem><para><option>--enable-fill</option> was specified during
+ build configuration.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>
+ <mallctl>config.lazy_lock</mallctl>
+ (<type>bool</type>)
+ <literal>r-</literal>
+ </term>
+ <listitem><para><option>--enable-lazy-lock</option> was specified
+ during build configuration.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>
+ <mallctl>config.prof</mallctl>
+ (<type>bool</type>)
+ <literal>r-</literal>
+ </term>
+ <listitem><para><option>--enable-prof</option> was specified during
+ build configuration.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>
+ <mallctl>config.prof_libgcc</mallctl>
+ (<type>bool</type>)
+ <literal>r-</literal>
+ </term>
+ <listitem><para><option>--disable-prof-libgcc</option> was not
+ specified during build configuration.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>
+ <mallctl>config.prof_libunwind</mallctl>
+ (<type>bool</type>)
+ <literal>r-</literal>
+ </term>
+ <listitem><para><option>--enable-prof-libunwind</option> was specified
+ during build configuration.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>
+ <mallctl>config.stats</mallctl>
+ (<type>bool</type>)
+ <literal>r-</literal>
+ </term>
+ <listitem><para><option>--enable-stats</option> was specified during
+ build configuration.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>
+ <mallctl>config.swap</mallctl>
+ (<type>bool</type>)
+ <literal>r-</literal>
+ </term>
+ <listitem><para><option>--enable-swap</option> was specified during
+ build configuration.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>
+ <mallctl>config.sysv</mallctl>
+ (<type>bool</type>)
+ <literal>r-</literal>
+ </term>
+ <listitem><para><option>--enable-sysv</option> was specified during
+ build configuration.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>
+ <mallctl>config.tcache</mallctl>
+ (<type>bool</type>)
+ <literal>r-</literal>
+ </term>
+ <listitem><para><option>--disable-tcache</option> was not specified
+ during build configuration.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>
+ <mallctl>config.tiny</mallctl>
+ (<type>bool</type>)
+ <literal>r-</literal>
+ </term>
+ <listitem><para><option>--disable-tiny</option> was not specified
+ during build configuration.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>
+ <mallctl>config.tls</mallctl>
+ (<type>bool</type>)
+ <literal>r-</literal>
+ </term>
+ <listitem><para><option>--disable-tls</option> was not specified during
+ build configuration.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>
+ <mallctl>config.xmalloc</mallctl>
+ (<type>bool</type>)
+ <literal>r-</literal>
+ </term>
+ <listitem><para><option>--enable-xmalloc</option> was specified during
+ build configuration.</para></listitem>
+ </varlistentry>
+
+ <varlistentry id="opt.abort">
+ <term>
+ <mallctl>opt.abort</mallctl>
+ (<type>bool</type>)
+ <literal>r-</literal>
+ </term>
+ <listitem><para>Abort-on-warning enabled/disabled. If true, most
+ warnings are fatal. The process will call
+ <citerefentry><refentrytitle>abort</refentrytitle>
+ <manvolnum>3</manvolnum></citerefentry> in these cases. This option is
+ disabled by default unless <option>--enable-debug</option> is
+ specified during configuration, in which case it is enabled by default.
+ </para></listitem>
+ </varlistentry>
+
+ <varlistentry id="opt.lg_qspace_max">
+ <term>
+ <mallctl>opt.lg_qspace_max</mallctl>
+ (<type>size_t</type>)
+ <literal>r-</literal>
+ </term>
+ <listitem><para>Size (log base 2) of the maximum size class that is a
+ multiple of the quantum (8 or 16 bytes, depending on architecture).
+ Above this size, cacheline spacing is used for size classes. The
+ default value is 128 bytes (2^7).</para></listitem>
+ </varlistentry>
+
+ <varlistentry id="opt.lg_cspace_max">
+ <term>
+ <mallctl>opt.lg_cspace_max</mallctl>
+ (<type>size_t</type>)
+ <literal>r-</literal>
+ </term>
+ <listitem><para>Size (log base 2) of the maximum size class that is a
+ multiple of the cacheline size (64). Above this size, subpage spacing
+ (256 bytes) is used for size classes. The default value is 512 bytes
+ (2^9).</para></listitem>
+ </varlistentry>
+
+ <varlistentry id="opt.lg_chunk">
+ <term>
+ <mallctl>opt.lg_chunk</mallctl>
+ (<type>size_t</type>)
+ <literal>r-</literal>
+ </term>
+ <listitem><para>Virtual memory chunk size (log base 2). The default
+ chunk size is 4 MiB (2^22).</para></listitem>
+ </varlistentry>
+
+ <varlistentry id="opt.narenas">
+ <term>
+ <mallctl>opt.narenas</mallctl>
+ (<type>size_t</type>)
+ <literal>r-</literal>
+ </term>
+ <listitem><para>Maximum number of arenas to use. The default maximum
+ number of arenas is four times the number of CPUs, or one if there is a
+ single CPU.</para></listitem>
+ </varlistentry>
+
+ <varlistentry id="opt.lg_dirty_mult">
+ <term>
+ <mallctl>opt.lg_dirty_mult</mallctl>
+ (<type>ssize_t</type>)
+ <literal>r-</literal>
+ </term>
+ <listitem><para>Per-arena minimum ratio (log base 2) of active to dirty
+ pages. Some dirty unused pages may be allowed to accumulate, within
+ the limit set by the ratio (or one chunk worth of dirty pages,
+ whichever is greater), before informing the kernel about some of those
+ pages via <citerefentry><refentrytitle>madvise</refentrytitle>
+ <manvolnum>2</manvolnum></citerefentry> or a similar system call. This
+ provides the kernel with sufficient information to recycle dirty pages
+ if physical memory becomes scarce and the pages remain unused. The
+ default minimum ratio is 32:1 (2^5:1); an option value of -1 will
+ disable dirty page purging.</para></listitem>
+ </varlistentry>
+
+ <varlistentry id="opt.stats_print">
+ <term>
+ <mallctl>opt.stats_print</mallctl>
+ (<type>bool</type>)
+ <literal>r-</literal>
+ </term>
+ <listitem><para>Enable/disable statistics printing at exit. If
+ enabled, the <function>malloc_stats_print<parameter/></function>
+ function is called at program exit via an
+ <citerefentry><refentrytitle>atexit</refentrytitle>
+ <manvolnum>3</manvolnum></citerefentry> function. If
+ <option>--enable-stats</option> is specified during configuration, this
+ has the potential to cause deadlock for a multi-threaded process that
+ exits while one or more threads are executing in the memory allocation
+ functions. Therefore, this option should only be used with care; it is
+ primarily intended as a performance tuning aid during application
+ development. This option is disabled by default.</para></listitem>
+ </varlistentry>
+
+ <varlistentry id="opt.junk">
+ <term>
+ <mallctl>opt.junk</mallctl>
+ (<type>bool</type>)
+ <literal>r-</literal>
+ [<option>--enable-fill</option>]
+ </term>
+ <listitem><para>Junk filling enabled/disabled. If enabled, each byte
+ of uninitialized allocated memory will be initialized to
+ <literal>0xa5</literal>. All deallocated memory will be initialized to
+ <literal>0x5a</literal>. This is intended for debugging and will
+ impact performance negatively. This option is disabled by default
+ unless <option>--enable-debug</option> is specified during
+ configuration, in which case it is enabled by default.</para></listitem>
+ </varlistentry>
+
+ <varlistentry id="opt.zero">
+ <term>
+ <mallctl>opt.zero</mallctl>
+ (<type>bool</type>)
+ <literal>r-</literal>
+ [<option>--enable-fill</option>]
+ </term>
+ <listitem><para>Zero filling enabled/disabled. If enabled, each byte
+ of uninitialized allocated memory will be initialized to 0. Note that
+ this initialization only happens once for each byte, so
+ <function>realloc<parameter/></function> and
+ <function>rallocm<parameter/></function> calls do not zero memory that
+ was previously allocated. This is intended for debugging and will
+ impact performance negatively. This option is disabled by default.
+ </para></listitem>
+ </varlistentry>
+
+ <varlistentry id="opt.sysv">
+ <term>
+ <mallctl>opt.sysv</mallctl>
+ (<type>bool</type>)
+ <literal>r-</literal>
+ [<option>--enable-sysv</option>]
+ </term>
+ <listitem><para>If enabled, attempting to allocate zero bytes will
+ return a <constant>NULL</constant> pointer instead of a valid pointer.
+ (The default behavior is to make a minimal allocation and return a
+ pointer to it.) This option is provided for System V compatibility.
+ This option is incompatible with the <link
+ linkend="opt.xmalloc"><mallctl>opt.xmalloc</mallctl></link> option.
+ This option is disabled by default.</para></listitem>
+ </varlistentry>
+
+ <varlistentry id="opt.xmalloc">
+ <term>
+ <mallctl>opt.xmalloc</mallctl>
+ (<type>bool</type>)
+ <literal>r-</literal>
+ [<option>--enable-xmalloc</option>]
+ </term>
+ <listitem><para>Abort-on-out-of-memory enabled/disabled. If enabled,
+ rather than returning failure for any allocation function, display a
+ diagnostic message on <constant>STDERR_FILENO</constant> and cause the
+ program to drop core (using
+ <citerefentry><refentrytitle>abort</refentrytitle>
+ <manvolnum>3</manvolnum></citerefentry>). If an application is
+ designed to depend on this behavior, set the option at compile time by
+ including the following in the source code:
+ <programlisting language="C"><![CDATA[
+malloc_conf = "xmalloc:true";]]></programlisting>
+ This option is disabled by default.</para></listitem>
+ </varlistentry>
+
+ <varlistentry id="opt.tcache">
+ <term>
+ <mallctl>opt.tcache</mallctl>
+ (<type>bool</type>)
+ <literal>r-</literal>
+ [<option>--enable-tcache</option>]
+ </term>
+ <listitem><para>Thread-specific caching enabled/disabled. When there
+ are multiple threads, each thread uses a thread-specific cache for
+ objects up to a certain size. Thread-specific caching allows many
+ allocations to be satisfied without performing any thread
+ synchronization, at the cost of increased memory use. See the
+ <link
+ linkend="opt.lg_tcache_gc_sweep"><mallctl>opt.lg_tcache_gc_sweep</mallctl></link>
+ and <link
+ linkend="opt.lg_tcache_max"><mallctl>opt.lg_tcache_max</mallctl></link>
+ options for related tuning information. This option is enabled by
+ default.</para></listitem>
+ </varlistentry>
+
+ <varlistentry id="opt.lg_tcache_gc_sweep">
+ <term>
+ <mallctl>opt.lg_tcache_gc_sweep</mallctl>
+ (<type>ssize_t</type>)
+ <literal>r-</literal>
+ [<option>--enable-tcache</option>]
+ </term>
+ <listitem><para>Approximate interval (log base 2) between full
+ thread-specific cache garbage collection sweeps, counted in terms of
+ thread-specific cache allocation/deallocation events. Garbage
+ collection is actually performed incrementally, one size class at a
+ time, in order to avoid large collection pauses. The default sweep
+ interval is 8192 (2^13); setting this option to -1 will disable garbage
+ collection.</para></listitem>
+ </varlistentry>
+
+ <varlistentry id="opt.lg_tcache_max">
+ <term>
+ <mallctl>opt.lg_tcache_max</mallctl>
+ (<type>size_t</type>)
+ <literal>r-</literal>
+ [<option>--enable-tcache</option>]
+ </term>
+ <listitem><para>Maximum size class (log base 2) to cache in the
+ thread-specific cache. At a minimum, all small size classes are
+ cached, and at a maximum all large size classes are cached. The
+ default maximum is 32 KiB (2^15).</para></listitem>
+ </varlistentry>
+
+ <varlistentry id="opt.prof">
+ <term>
+ <mallctl>opt.prof</mallctl>
+ (<type>bool</type>)
+ <literal>r-</literal>
+ [<option>--enable-prof</option>]
+ </term>
+ <listitem><para>Memory profiling enabled/disabled. If enabled, profile
+ memory allocation activity, and use an
+ <citerefentry><refentrytitle>atexit</refentrytitle>
+ <manvolnum>3</manvolnum></citerefentry> function to dump final memory
+ usage to a file named according to the pattern
+ <filename><prefix>.<pid>.<seq>.f.heap</filename>,
+ where <literal><prefix></literal> is controlled by the <link
+ linkend="opt.prof_prefix"><mallctl>opt.prof_prefix</mallctl></link>
+ option. See the <link
+ linkend="opt.lg_prof_bt_max"><mallctl>opt.lg_prof_bt_max</mallctl></link>
+ option for backtrace depth control. See the <link
+ linkend="opt.prof_active"><mallctl>opt.prof_active</mallctl></link>
+ option for on-the-fly activation/deactivation. See the <link
+ linkend="opt.lg_prof_sample"><mallctl>opt.lg_prof_sample</mallctl></link>
+ option for probabilistic sampling control. See the <link
+ linkend="opt.prof_accum"><mallctl>opt.prof_accum</mallctl></link>
+ option for control of cumulative sample reporting. See the <link
+ linkend="opt.lg_prof_tcmax"><mallctl>opt.lg_prof_tcmax</mallctl></link>
+ option for control of per thread backtrace caching. See the <link
+ linkend="opt.lg_prof_interval"><mallctl>opt.lg_prof_interval</mallctl></link>
+ option for information on interval-triggered profile dumping, and the
+ <link linkend="opt.prof_gdump"><mallctl>opt.prof_gdump</mallctl></link>
+ option for information on high-water-triggered profile dumping.
+ Profile output is compatible with the included <command>pprof</command>
+ Perl script, which originates from the <ulink
+ url="http://code.google.com/p/google-perftools/">google-perftools
+ package</ulink>.</para></listitem>
+ </varlistentry>
+
+ <varlistentry id="opt.prof_prefix">
+ <term>
+ <mallctl>opt.prof_prefix</mallctl>
+ (<type>const char *</type>)
+ <literal>r-</literal>
+ [<option>--enable-prof</option>]
+ </term>
+ <listitem><para>Filename prefix for profile dumps. If the prefix is
+ set to the empty string, no automatic dumps will occur; this is
+ primarily useful for disabling the automatic final heap dump (which
+ also disables leak reporting, if enabled). The default prefix is
+ <filename>jeprof</filename>.</para></listitem>
+ </varlistentry>
+
+ <varlistentry id="opt.lg_prof_bt_max">
+ <term>
+ <mallctl>opt.lg_prof_bt_max</mallctl>
+ (<type>size_t</type>)
+ <literal>r-</literal>
+ [<option>--enable-prof</option>]
+ </term>
+ <listitem><para>Maximum backtrace depth (log base 2) when profiling
+ memory allocation activity. The default is 128 (2^7).</para></listitem>
+ </varlistentry>
+
+ <varlistentry id="opt.prof_active">
+ <term>
+ <mallctl>opt.prof_active</mallctl>
+ (<type>bool</type>)
+ <literal>r-</literal>
+ [<option>--enable-prof</option>]
+ </term>
+ <listitem><para>Profiling activated/deactivated. This is a secondary
+ control mechanism that makes it possible to start the application with
+ profiling enabled (see the <link
+ linkend="opt.prof"><mallctl>opt.prof</mallctl></link> option) but
+ inactive, then toggle profiling at any time during program execution
+ with the <link
+ linkend="prof.active"><mallctl>prof.active</mallctl></link> mallctl.
+ This option is enabled by default.</para></listitem>
+ </varlistentry>
+
+ <varlistentry id="opt.lg_prof_sample">
+ <term>
+ <mallctl>opt.lg_prof_sample</mallctl>
+ (<type>ssize_t</type>)
+ <literal>r-</literal>
+ [<option>--enable-prof</option>]
+ </term>
+ <listitem><para>Average interval (log base 2) between allocation
+ samples, as measured in bytes of allocation activity. Increasing the
+ sampling interval decreases profile fidelity, but also decreases the
+ computational overhead. The default sample interval is 1 (2^0) (i.e.
+ all allocations are sampled).</para></listitem>
+ </varlistentry>
+
+ <varlistentry id="opt.prof_accum">
+ <term>
+ <mallctl>opt.prof_accum</mallctl>
+ (<type>bool</type>)
+ <literal>r-</literal>
+ [<option>--enable-prof</option>]
+ </term>
+ <listitem><para>Reporting of cumulative object/byte counts in profile
+ dumps enabled/disabled. If this option is enabled, every unique
+ backtrace must be stored for the duration of execution. Depending on
+ the application, this can impose a large memory overhead, and the
+ cumulative counts are not always of interest. See the
+ <link
+ linkend="opt.lg_prof_tcmax"><mallctl>opt.lg_prof_tcmax</mallctl></link>
+ option for control of per thread backtrace caching, which has important
+ interactions. This option is enabled by default.</para></listitem>
+ </varlistentry>
+
+ <varlistentry id="opt.lg_prof_tcmax">
+ <term>
+ <mallctl>opt.lg_prof_tcmax</mallctl>
+ (<type>ssize_t</type>)
+ <literal>r-</literal>
+ [<option>--enable-prof</option>]
+ </term>
+ <listitem><para>Maximum per thread backtrace cache (log base 2) used
+ for heap profiling. A backtrace can only be discarded if the
+ <link linkend="opt.prof_accum"><mallctl>opt.prof_accum</mallctl></link>
+ option is disabled, and no thread caches currently refer to the
+ backtrace. Therefore, a backtrace cache limit should be imposed if the
+ intention is to limit how much memory is used by backtraces. By
+ default, no limit is imposed (encoded as -1).
+ </para></listitem>
+ </varlistentry>
+
+ <varlistentry id="opt.lg_prof_interval">
+ <term>
+ <mallctl>opt.lg_prof_interval</mallctl>
+ (<type>ssize_t</type>)
+ <literal>r-</literal>
+ [<option>--enable-prof</option>]
+ </term>
+ <listitem><para>Average interval (log base 2) between memory profile
+ dumps, as measured in bytes of allocation activity. The actual
+ interval between dumps may be sporadic because decentralized allocation
+ counters are used to avoid synchronization bottlenecks. Profiles are
+ dumped to files named according to the pattern
+ <filename><prefix>.<pid>.<seq>.i<iseq>.heap</filename>,
+ where <literal><prefix></literal> is controlled by the
+ <link
+ linkend="opt.prof_prefix"><mallctl>opt.prof_prefix</mallctl></link>
+ option. By default, interval-triggered profile dumping is disabled
+ (encoded as -1).
+ </para></listitem>
+ </varlistentry>
+
+ <varlistentry id="opt.prof_gdump">
+ <term>
+ <mallctl>opt.prof_gdump</mallctl>
+ (<type>bool</type>)
+ <literal>r-</literal>
+ [<option>--enable-prof</option>]
+ </term>
+ <listitem><para>Trigger a memory profile dump every time the total
+ virtual memory exceeds the previous maximum. Profiles are dumped to
+ files named according to the pattern
+ <filename><prefix>.<pid>.<seq>.u<useq>.heap</filename>,
+ where <literal><prefix></literal> is controlled by the <link
+ linkend="opt.prof_prefix"><mallctl>opt.prof_prefix</mallctl></link>
+ option. This option is disabled by default.</para></listitem>
+ </varlistentry>
+
+ <varlistentry id="opt.prof_leak">
+ <term>
+ <mallctl>opt.prof_leak</mallctl>
+ (<type>bool</type>)
+ <literal>r-</literal>
+ [<option>--enable-prof</option>]
+ </term>
+ <listitem><para>Leak reporting enabled/disabled. If enabled, use an
+ <citerefentry><refentrytitle>atexit</refentrytitle>
+ <manvolnum>3</manvolnum></citerefentry> function to report memory leaks
+ detected by allocation sampling. See the
+ <link
+ linkend="opt.lg_prof_bt_max"><mallctl>opt.lg_prof_bt_max</mallctl></link>
+ option for backtrace depth control. See the
+ <link linkend="opt.prof"><mallctl>opt.prof</mallctl></link> option for
+ information on analyzing heap profile output. This option is disabled
+ by default.</para></listitem>
+ </varlistentry>
+
+ <varlistentry id="opt.overcommit">
+ <term>
+ <mallctl>opt.overcommit</mallctl>
+ (<type>bool</type>)
+ <literal>r-</literal>
+ [<option>--enable-swap</option>]
+ </term>
+ <listitem><para>Over-commit enabled/disabled. If enabled, over-commit
+ memory as a side effect of using anonymous
+ <citerefentry><refentrytitle>mmap</refentrytitle>
+ <manvolnum>2</manvolnum></citerefentry> or
+ <citerefentry><refentrytitle>sbrk</refentrytitle>
+ <manvolnum>2</manvolnum></citerefentry> for virtual memory allocation.
+ In order for overcommit to be disabled, the <link
+ linkend="swap.fds"><mallctl>swap.fds</mallctl></link> mallctl must have
+ been successfully written to. This option is enabled by
+ default.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>
+ <mallctl>tcache.flush</mallctl>
+ (<type>void</type>)
+ <literal>--</literal>
+ [<option>--enable-tcache</option>]
+ </term>
+ <listitem><para>Flush calling thread's tcache. This interface releases
+ all cached objects and internal data structures associated with the
+ calling thread's thread-specific cache. Ordinarily, this interface
+ need not be called, since automatic periodic incremental garbage
+ collection occurs, and the thread cache is automatically discarded when
+ a thread exits. However, garbage collection is triggered by allocation
+ activity, so it is possible for a thread that stops
+ allocating/deallocating to retain its cache indefinitely, in which case
+ the developer may find manual flushing useful.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>
+ <mallctl>thread.arena</mallctl>
+ (<type>unsigned</type>)
+ <literal>rw</literal>
+ </term>
+ <listitem><para>Get or set the arena associated with the calling
+ thread. The arena index must be less than the maximum number of arenas
+ (see the <link
+ linkend="arenas.narenas"><mallctl>arenas.narenas</mallctl></link>
+ mallctl). If the specified arena was not initialized beforehand (see
+ the <link
+ linkend="arenas.initialized"><mallctl>arenas.initialized</mallctl></link>
+ mallctl), it will be automatically initialized as a side effect of
+ calling this interface.</para></listitem>
+ </varlistentry>
+
+ <varlistentry id="thread.allocated">
+ <term>
+ <mallctl>thread.allocated</mallctl>
+ (<type>uint64_t</type>)
+ <literal>r-</literal>
+ [<option>--enable-stats</option>]
+ </term>
+ <listitem><para>Get the total number of bytes ever allocated by the
+ calling thread. This counter has the potential to wrap around; it is
+ up to the application to appropriately interpret the counter in such
+ cases.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>
+ <mallctl>thread.allocatedp</mallctl>
+ (<type>uint64_t *</type>)
+ <literal>r-</literal>
+ [<option>--enable-stats</option>]
+ </term>
+ <listitem><para>Get a pointer to the the value that is returned by the
+ <link
+ linkend="thread.allocated"><mallctl>thread.allocated</mallctl></link>
+ mallctl. This is useful for avoiding the overhead of repeated
+ <function>mallctl*<parameter/></function> calls.</para></listitem>
+ </varlistentry>
+
+ <varlistentry id="thread.deallocated">
+ <term>
+ <mallctl>thread.deallocated</mallctl>
+ (<type>uint64_t</type>)
+ <literal>r-</literal>
+ [<option>--enable-stats</option>]
+ </term>
+ <listitem><para>Get the total number of bytes ever deallocated by the
+ calling thread. This counter has the potential to wrap around; it is
+ up to the application to appropriately interpret the counter in such
+ cases.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>
+ <mallctl>thread.deallocatedp</mallctl>
+ (<type>uint64_t *</type>)
+ <literal>r-</literal>
+ [<option>--enable-stats</option>]
+ </term>
+ <listitem><para>Get a pointer to the the value that is returned by the
+ <link
+ linkend="thread.deallocated"><mallctl>thread.deallocated</mallctl></link>
+ mallctl. This is useful for avoiding the overhead of repeated
+ <function>mallctl*<parameter/></function> calls.</para></listitem>
+ </varlistentry>
+
+ <varlistentry id="arenas.narenas">
+ <term>
+ <mallctl>arenas.narenas</mallctl>
+ (<type>unsigned</type>)
+ <literal>r-</literal>
+ </term>
+ <listitem><para>Maximum number of arenas.</para></listitem>
+ </varlistentry>
+
+ <varlistentry id="arenas.initialized">
+ <term>
+ <mallctl>arenas.initialized</mallctl>
+ (<type>bool *</type>)
+ <literal>r-</literal>
+ </term>
+ <listitem><para>An array of <link
+ linkend="arenas.narenas"><mallctl>arenas.narenas</mallctl></link>
+ booleans. Each boolean indicates whether the corresponding arena is
+ initialized.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>
+ <mallctl>arenas.quantum</mallctl>
+ (<type>size_t</type>)
+ <literal>r-</literal>
+ </term>
+ <listitem><para>Quantum size.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>
+ <mallctl>arenas.cacheline</mallctl>
+ (<type>size_t</type>)
+ <literal>r-</literal>
+ </term>
+ <listitem><para>Assumed cacheline size.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>
+ <mallctl>arenas.subpage</mallctl>
+ (<type>size_t</type>)
+ <literal>r-</literal>
+ </term>
+ <listitem><para>Subpage size class interval.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>
+ <mallctl>arenas.pagesize</mallctl>
+ (<type>size_t</type>)
+ <literal>r-</literal>
+ </term>
+ <listitem><para>Page size.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>
+ <mallctl>arenas.chunksize</mallctl>
+ (<type>size_t</type>)
+ <literal>r-</literal>
+ </term>
+ <listitem><para>Chunk size.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>
+ <mallctl>arenas.tspace_min</mallctl>
+ (<type>size_t</type>)
+ <literal>r-</literal>
+ </term>
+ <listitem><para>Minimum tiny size class. Tiny size classes are powers
+ of two.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>
+ <mallctl>arenas.tspace_max</mallctl>
+ (<type>size_t</type>)
+ <literal>r-</literal>
+ </term>
+ <listitem><para>Maximum tiny size class. Tiny size classes are powers
+ of two.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>
+ <mallctl>arenas.qspace_min</mallctl>
+ (<type>size_t</type>)
+ <literal>r-</literal>
+ </term>
+ <listitem><para>Minimum quantum-spaced size class.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>
+ <mallctl>arenas.qspace_max</mallctl>
+ (<type>size_t</type>)
+ <literal>r-</literal>
+ </term>
+ <listitem><para>Maximum quantum-spaced size class.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>
+ <mallctl>arenas.cspace_min</mallctl>
+ (<type>size_t</type>)
+ <literal>r-</literal>
+ </term>
+ <listitem><para>Minimum cacheline-spaced size class.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>
+ <mallctl>arenas.cspace_max</mallctl>
+ (<type>size_t</type>)
+ <literal>r-</literal>
+ </term>
+ <listitem><para>Maximum cacheline-spaced size class.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>
+ <mallctl>arenas.sspace_min</mallctl>
+ (<type>size_t</type>)
+ <literal>r-</literal>
+ </term>
+ <listitem><para>Minimum subpage-spaced size class.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>
+ <mallctl>arenas.sspace_max</mallctl>
+ (<type>size_t</type>)
+ <literal>r-</literal>
+ </term>
+ <listitem><para>Maximum subpage-spaced size class.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>
+ <mallctl>arenas.tcache_max</mallctl>
+ (<type>size_t</type>)
+ <literal>r-</literal>
+ [<option>--enable-tcache</option>]
+ </term>
+ <listitem><para>Maximum thread-cached size class.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>
+ <mallctl>arenas.ntbins</mallctl>
+ (<type>unsigned</type>)
+ <literal>r-</literal>
+ </term>
+ <listitem><para>Number of tiny bin size classes.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>
+ <mallctl>arenas.nqbins</mallctl>
+ (<type>unsigned</type>)
+ <literal>r-</literal>
+ </term>
+ <listitem><para>Number of quantum-spaced bin size
+ classes.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>
+ <mallctl>arenas.ncbins</mallctl>
+ (<type>unsigned</type>)
+ <literal>r-</literal>
+ </term>
+ <listitem><para>Number of cacheline-spaced bin size
+ classes.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>
+ <mallctl>arenas.nsbins</mallctl>
+ (<type>unsigned</type>)
+ <literal>r-</literal>
+ </term>
+ <listitem><para>Number of subpage-spaced bin size
+ classes.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>
+ <mallctl>arenas.nbins</mallctl>
+ (<type>unsigned</type>)
+ <literal>r-</literal>
+ </term>
+ <listitem><para>Total number of bin size classes.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>
+ <mallctl>arenas.nhbins</mallctl>
+ (<type>unsigned</type>)
+ <literal>r-</literal>
+ [<option>--enable-tcache</option>]
+ </term>
+ <listitem><para>Total number of thread cache bin size
+ classes.</para></listitem>
+ </varlistentry>
+
+ <varlistentry id="arenas.bin.i.size">
+ <term>
+ <mallctl>arenas.bin.<i>.size</mallctl>
+ (<type>size_t</type>)
+ <literal>r-</literal>
+ </term>
+ <listitem><para>Maximum size supported by size class.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>
+ <mallctl>arenas.bin.<i>.nregs</mallctl>
+ (<type>uint32_t</type>)
+ <literal>r-</literal>
+ </term>
+ <listitem><para>Number of regions per page run.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>
+ <mallctl>arenas.bin.<i>.run_size</mallctl>
+ (<type>size_t</type>)
+ <literal>r-</literal>
+ </term>
+ <listitem><para>Number of bytes per page run.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>
+ <mallctl>arenas.nlruns</mallctl>
+ (<type>size_t</type>)
+ <literal>r-</literal>
+ </term>
+ <listitem><para>Total number of large size classes.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>
+ <mallctl>arenas.lrun.<i>.size</mallctl>
+ (<type>size_t</type>)
+ <literal>r-</literal>
+ </term>
+ <listitem><para>Maximum size supported by this large size
+ class.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>
+ <mallctl>arenas.purge</mallctl>
+ (<type>unsigned</type>)
+ <literal>-w</literal>
+ </term>
+ <listitem><para>Purge unused dirty pages for the specified arena, or
+ for all arenas if none is specified.</para></listitem>
+ </varlistentry>
+
+ <varlistentry id="prof.active">
+ <term>
+ <mallctl>prof.active</mallctl>
+ (<type>bool</type>)
+ <literal>rw</literal>
+ [<option>--enable-prof</option>]
+ </term>
+ <listitem><para>Control whether sampling is currently active. See the
+ <link
+ linkend="opt.prof_active"><mallctl>opt.prof_active</mallctl></link>
+ option for additional information.
+ </para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>
+ <mallctl>prof.dump</mallctl>
+ (<type>const char *</type>)
+ <literal>-w</literal>
+ [<option>--enable-prof</option>]
+ </term>
+ <listitem><para>Dump a memory profile to the specified file, or if NULL
+ is specified, to a file according to the pattern
+ <filename><prefix>.<pid>.<seq>.m<mseq>.heap</filename>,
+ where <literal><prefix></literal> is controlled by the
+ <link
+ linkend="opt.prof_prefix"><mallctl>opt.prof_prefix</mallctl></link>
+ option.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>
+ <mallctl>prof.interval</mallctl>
+ (<type>uint64_t</type>)
+ <literal>r-</literal>
+ [<option>--enable-prof</option>]
+ </term>
+ <listitem><para>Average number of bytes allocated between
+ inverval-based profile dumps. See the
+ <link
+ linkend="opt.lg_prof_interval"><mallctl>opt.lg_prof_interval</mallctl></link>
+ option for additional information.</para></listitem>
+ </varlistentry>
+
+ <varlistentry id="stats.cactive">
+ <term>
+ <mallctl>stats.cactive</mallctl>
+ (<type>size_t *</type>)
+ <literal>r-</literal>
+ [<option>--enable-stats</option>]
+ </term>
+ <listitem><para>Pointer to a counter that contains an approximate count
+ of the current number of bytes in active pages. The estimate may be
+ high, but never low, because each arena rounds up to the nearest
+ multiple of the chunk size when computing its contribution to the
+ counter. Note that the <link
+ linkend="epoch"><mallctl>epoch</mallctl></link> mallctl has no bearing
+ on this counter. Furthermore, counter consistency is maintained via
+ atomic operations, so it is necessary to use an atomic operation in
+ order to guarantee a consistent read when dereferencing the pointer.
+ </para></listitem>
+ </varlistentry>
+
+ <varlistentry id="stats.allocated">
+ <term>
+ <mallctl>stats.allocated</mallctl>
+ (<type>size_t</type>)
+ <literal>r-</literal>
+ [<option>--enable-stats</option>]
+ </term>
+ <listitem><para>Total number of bytes allocated by the
+ application.</para></listitem>
+ </varlistentry>
+
+ <varlistentry id="stats.active">
+ <term>
+ <mallctl>stats.active</mallctl>
+ (<type>size_t</type>)
+ <literal>r-</literal>
+ [<option>--enable-stats</option>]
+ </term>
+ <listitem><para>Total number of bytes in active pages allocated by the
+ application. This is a multiple of the page size, and greater than or
+ equal to <link
+ linkend="stats.allocated"><mallctl>stats.allocated</mallctl></link>.
+ </para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>
+ <mallctl>stats.mapped</mallctl>
+ (<type>size_t</type>)
+ <literal>r-</literal>
+ [<option>--enable-stats</option>]
+ </term>
+ <listitem><para>Total number of bytes in chunks mapped on behalf of the
+ application. This is a multiple of the chunk size, and is at least as
+ large as <link
+ linkend="stats.active"><mallctl>stats.active</mallctl></link>. This
+ does not include inactive chunks backed by swap files. his does not
+ include inactive chunks embedded in the DSS.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>
+ <mallctl>stats.chunks.current</mallctl>
+ (<type>size_t</type>)
+ <literal>r-</literal>
+ [<option>--enable-stats</option>]
+ </term>
+ <listitem><para>Total number of chunks actively mapped on behalf of the
+ application. This does not include inactive chunks backed by swap
+ files. This does not include inactive chunks embedded in the DSS.
+ </para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>
+ <mallctl>stats.chunks.total</mallctl>
+ (<type>uint64_t</type>)
+ <literal>r-</literal>
+ [<option>--enable-stats</option>]
+ </term>
+ <listitem><para>Cumulative number of chunks allocated.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>
+ <mallctl>stats.chunks.high</mallctl>
+ (<type>size_t</type>)
+ <literal>r-</literal>
+ [<option>--enable-stats</option>]
+ </term>
+ <listitem><para>Maximum number of active chunks at any time thus far.
+ </para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>
+ <mallctl>stats.huge.allocated</mallctl>
+ (<type>size_t</type>)
+ <literal>r-</literal>
+ [<option>--enable-stats</option>]
+ </term>
+ <listitem><para>Number of bytes currently allocated by huge objects.
+ </para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>
+ <mallctl>stats.huge.nmalloc</mallctl>
+ (<type>uint64_t</type>)
+ <literal>r-</literal>
+ [<option>--enable-stats</option>]
+ </term>
+ <listitem><para>Cumulative number of huge allocation requests.
+ </para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>
+ <mallctl>stats.huge.ndalloc</mallctl>
+ (<type>uint64_t</type>)
+ <literal>r-</literal>
+ [<option>--enable-stats</option>]
+ </term>
+ <listitem><para>Cumulative number of huge deallocation requests.
+ </para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>
+ <mallctl>stats.arenas.<i>.nthreads</mallctl>
+ (<type>unsigned</type>)
+ <literal>r-</literal>
+ </term>
+ <listitem><para>Number of threads currently assigned to
+ arena.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>
+ <mallctl>stats.arenas.<i>.pactive</mallctl>
+ (<type>size_t</type>)
+ <literal>r-</literal>
+ </term>
+ <listitem><para>Number of pages in active runs.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>
+ <mallctl>stats.arenas.<i>.pdirty</mallctl>
+ (<type>size_t</type>)
+ <literal>r-</literal>
+ </term>
+ <listitem><para>Number of pages within unused runs that are potentially
+ dirty, and for which <function>madvise<parameter>...</parameter>
+ <parameter><constant>MADV_DONTNEED</constant></parameter></function> or
+ similar has not been called.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>
+ <mallctl>stats.arenas.<i>.mapped</mallctl>
+ (<type>size_t</type>)
+ <literal>r-</literal>
+ [<option>--enable-stats</option>]
+ </term>
+ <listitem><para>Number of mapped bytes.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>
+ <mallctl>stats.arenas.<i>.npurge</mallctl>
+ (<type>uint64_t</type>)
+ <literal>r-</literal>
+ [<option>--enable-stats</option>]
+ </term>
+ <listitem><para>Number of dirty page purge sweeps performed.
+ </para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>
+ <mallctl>stats.arenas.<i>.nmadvise</mallctl>
+ (<type>uint64_t</type>)
+ <literal>r-</literal>
+ [<option>--enable-stats</option>]
+ </term>
+ <listitem><para>Number of <function>madvise<parameter>...</parameter>
+ <parameter><constant>MADV_DONTNEED</constant></parameter></function> or
+ similar calls made to purge dirty pages.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>
+ <mallctl>stats.arenas.<i>.npurged</mallctl>
+ (<type>uint64_t</type>)
+ <literal>r-</literal>
+ [<option>--enable-stats</option>]
+ </term>
+ <listitem><para>Number of pages purged.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>
+ <mallctl>stats.arenas.<i>.small.allocated</mallctl>
+ (<type>size_t</type>)
+ <literal>r-</literal>
+ [<option>--enable-stats</option>]
+ </term>
+ <listitem><para>Number of bytes currently allocated by small objects.
+ </para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>
+ <mallctl>stats.arenas.<i>.small.nmalloc</mallctl>
+ (<type>uint64_t</type>)
+ <literal>r-</literal>
+ [<option>--enable-stats</option>]
+ </term>
+ <listitem><para>Cumulative number of allocation requests served by
+ small bins.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>
+ <mallctl>stats.arenas.<i>.small.ndalloc</mallctl>
+ (<type>uint64_t</type>)
+ <literal>r-</literal>
+ [<option>--enable-stats</option>]
+ </term>
+ <listitem><para>Cumulative number of small objects returned to bins.
+ </para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>
+ <mallctl>stats.arenas.<i>.small.nrequests</mallctl>
+ (<type>uint64_t</type>)
+ <literal>r-</literal>
+ [<option>--enable-stats</option>]
+ </term>
+ <listitem><para>Cumulative number of small allocation requests.
+ </para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>
+ <mallctl>stats.arenas.<i>.large.allocated</mallctl>
+ (<type>size_t</type>)
+ <literal>r-</literal>
+ [<option>--enable-stats</option>]
+ </term>
+ <listitem><para>Number of bytes currently allocated by large objects.
+ </para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>
+ <mallctl>stats.arenas.<i>.large.nmalloc</mallctl>
+ (<type>uint64_t</type>)
+ <literal>r-</literal>
+ [<option>--enable-stats</option>]
+ </term>
+ <listitem><para>Cumulative number of large allocation requests served
+ directly by the arena.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>
+ <mallctl>stats.arenas.<i>.large.ndalloc</mallctl>
+ (<type>uint64_t</type>)
+ <literal>r-</literal>
+ [<option>--enable-stats</option>]
+ </term>
+ <listitem><para>Cumulative number of large deallocation requests served
+ directly by the arena.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>
+ <mallctl>stats.arenas.<i>.large.nrequests</mallctl>
+ (<type>uint64_t</type>)
+ <literal>r-</literal>
+ [<option>--enable-stats</option>]
+ </term>
+ <listitem><para>Cumulative number of large allocation requests.
+ </para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>
+ <mallctl>stats.arenas.<i>.bins.<j>.allocated</mallctl>
+ (<type>size_t</type>)
+ <literal>r-</literal>
+ [<option>--enable-stats</option>]
+ </term>
+ <listitem><para>Current number of bytes allocated by
+ bin.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>
+ <mallctl>stats.arenas.<i>.bins.<j>.nmalloc</mallctl>
+ (<type>uint64_t</type>)
+ <literal>r-</literal>
+ [<option>--enable-stats</option>]
+ </term>
+ <listitem><para>Cumulative number of allocations served by bin.
+ </para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>
+ <mallctl>stats.arenas.<i>.bins.<j>.ndalloc</mallctl>
+ (<type>uint64_t</type>)
+ <literal>r-</literal>
+ [<option>--enable-stats</option>]
+ </term>
+ <listitem><para>Cumulative number of allocations returned to bin.
+ </para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>
+ <mallctl>stats.arenas.<i>.bins.<j>.nrequests</mallctl>
+ (<type>uint64_t</type>)
+ <literal>r-</literal>
+ [<option>--enable-stats</option>]
+ </term>
+ <listitem><para>Cumulative number of allocation
+ requests.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>
+ <mallctl>stats.arenas.<i>.bins.<j>.nfills</mallctl>
+ (<type>uint64_t</type>)
+ <literal>r-</literal>
+ [<option>--enable-stats</option> <option>--enable-tcache</option>]
+ </term>
+ <listitem><para>Cumulative number of tcache fills.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>
+ <mallctl>stats.arenas.<i>.bins.<j>.nflushes</mallctl>
+ (<type>uint64_t</type>)
+ <literal>r-</literal>
+ [<option>--enable-stats</option> <option>--enable-tcache</option>]
+ </term>
+ <listitem><para>Cumulative number of tcache flushes.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>
+ <mallctl>stats.arenas.<i>.bins.<j>.nruns</mallctl>
+ (<type>uint64_t</type>)
+ <literal>r-</literal>
+ [<option>--enable-stats</option>]
+ </term>
+ <listitem><para>Cumulative number of runs created.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>
+ <mallctl>stats.arenas.<i>.bins.<j>.nreruns</mallctl>
+ (<type>uint64_t</type>)
+ <literal>r-</literal>
+ [<option>--enable-stats</option>]
+ </term>
+ <listitem><para>Cumulative number of times the current run from which
+ to allocate changed.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>
+ <mallctl>stats.arenas.<i>.bins.<j>.highruns</mallctl>
+ (<type>size_t</type>)
+ <literal>r-</literal>
+ [<option>--enable-stats</option>]
+ </term>
+ <listitem><para>Maximum number of runs at any time thus far.
+ </para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>
+ <mallctl>stats.arenas.<i>.bins.<j>.curruns</mallctl>
+ (<type>size_t</type>)
+ <literal>r-</literal>
+ [<option>--enable-stats</option>]
+ </term>
+ <listitem><para>Current number of runs.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>
+ <mallctl>stats.arenas.<i>.lruns.<j>.nmalloc</mallctl>
+ (<type>uint64_t</type>)
+ <literal>r-</literal>
+ [<option>--enable-stats</option>]
+ </term>
+ <listitem><para>Cumulative number of allocation requests for this size
+ class served directly by the arena.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>
+ <mallctl>stats.arenas.<i>.lruns.<j>.ndalloc</mallctl>
+ (<type>uint64_t</type>)
+ <literal>r-</literal>
+ [<option>--enable-stats</option>]
+ </term>
+ <listitem><para>Cumulative number of deallocation requests for this
+ size class served directly by the arena.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>
+ <mallctl>stats.arenas.<i>.lruns.<j>.nrequests</mallctl>
+ (<type>uint64_t</type>)
+ <literal>r-</literal>
+ [<option>--enable-stats</option>]
+ </term>
+ <listitem><para>Cumulative number of allocation requests for this size
+ class.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>
+ <mallctl>stats.arenas.<i>.lruns.<j>.highruns</mallctl>
+ (<type>size_t</type>)
+ <literal>r-</literal>
+ [<option>--enable-stats</option>]
+ </term>
+ <listitem><para>Maximum number of runs at any time thus far for this
+ size class.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>
+ <mallctl>stats.arenas.<i>.lruns.<j>.curruns</mallctl>
+ (<type>size_t</type>)
+ <literal>r-</literal>
+ [<option>--enable-stats</option>]
+ </term>
+ <listitem><para>Current number of runs for this size class.
+ </para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>
+ <mallctl>swap.avail</mallctl>
+ (<type>size_t</type>)
+ <literal>r-</literal>
+ [<option>--enable-stats --enable-swap</option>]
+ </term>
+ <listitem><para>Number of swap file bytes that are currently not
+ associated with any chunk (i.e. mapped, but otherwise completely
+ unmanaged).</para></listitem>
+ </varlistentry>
+
+ <varlistentry id="swap.prezeroed">
+ <term>
+ <mallctl>swap.prezeroed</mallctl>
+ (<type>bool</type>)
+ <literal>rw</literal>
+ [<option>--enable-swap</option>]
+ </term>
+ <listitem><para>If true, the allocator assumes that the swap file(s)
+ contain nothing but nil bytes. If this assumption is violated,
+ allocator behavior is undefined. This value becomes read-only after
+ <link linkend="swap.fds"><mallctl>swap.fds</mallctl></link> is
+ successfully written to.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>
+ <mallctl>swap.nfds</mallctl>
+ (<type>size_t</type>)
+ <literal>r-</literal>
+ [<option>--enable-swap</option>]
+ </term>
+ <listitem><para>Number of file descriptors in use for swap.
+ </para></listitem>
+ </varlistentry>
+
+ <varlistentry id="swap.fds">
+ <term>
+ <mallctl>swap.fds</mallctl>
+ (<type>int *</type>)
+ <literal>rw</literal>
+ [<option>--enable-swap</option>]
+ </term>
+ <listitem><para>When written to, the files associated with the
+ specified file descriptors are contiguously mapped via
+ <citerefentry><refentrytitle>mmap</refentrytitle>
+ <manvolnum>2</manvolnum></citerefentry>. The resulting virtual memory
+ region is preferred over anonymous
+ <citerefentry><refentrytitle>mmap</refentrytitle>
+ <manvolnum>2</manvolnum></citerefentry> and
+ <citerefentry><refentrytitle>sbrk</refentrytitle>
+ <manvolnum>2</manvolnum></citerefentry> memory. Note that if a file's
+ size is not a multiple of the page size, it is automatically truncated
+ to the nearest page size multiple. See the
+ <link linkend="swap.prezeroed"><mallctl>swap.prezeroed</mallctl></link>
+ mallctl for specifying that the files are pre-zeroed.</para></listitem>
+ </varlistentry>
+ </variablelist>
+ </refsect1>
+ <refsect1 id="debugging_malloc_problems">
+ <title>DEBUGGING MALLOC PROBLEMS</title>
+ <para>When debugging, it is a good idea to configure/build jemalloc with
+ the <option>--enable-debug</option> and <option>--enable-fill</option>
+ options, and recompile the program with suitable options and symbols for
+ debugger support. When so configured, jemalloc incorporates a wide variety
+ of run-time assertions that catch application errors such as double-free,
+ write-after-free, etc.</para>
+
+ <para>Programs often accidentally depend on “uninitialized”
+ memory actually being filled with zero bytes. Junk filling
+ (see the <link linkend="opt.junk"><mallctl>opt.junk</mallctl></link>
+ option) tends to expose such bugs in the form of obviously incorrect
+ results and/or coredumps. Conversely, zero
+ filling (see the <link
+ linkend="opt.zero"><mallctl>opt.zero</mallctl></link> option) eliminates
+ the symptoms of such bugs. Between these two options, it is usually
+ possible to quickly detect, diagnose, and eliminate such bugs.</para>
+
+ <para>This implementation does not provide much detail about the problems
+ it detects, because the performance impact for storing such information
+ would be prohibitive. There are a number of allocator implementations
+ available on the Internet which focus on detecting and pinpointing problems
+ by trading performance for extra sanity checks and detailed
+ diagnostics.</para>
+ </refsect1>
+ <refsect1 id="diagnostic_messages">
+ <title>DIAGNOSTIC MESSAGES</title>
+ <para>If any of the memory allocation/deallocation functions detect an
+ error or warning condition, a message will be printed to file descriptor
+ <constant>STDERR_FILENO</constant>. Errors will result in the process
+ dumping core. If the <link
+ linkend="opt.abort"><mallctl>opt.abort</mallctl></link> option is set, most
+ warnings are treated as errors.</para>
+
+ <para>The <varname>malloc_message</varname> variable allows the programmer
+ to override the function which emits the text strings forming the errors
+ and warnings if for some reason the <constant>STDERR_FILENO</constant> file
+ descriptor is not suitable for this.
+ <function>malloc_message<parameter/></function> takes the
+ <parameter>cbopaque</parameter> pointer argument that is
+ <constant>NULL</constant> unless overridden by the arguments in a call to
+ <function>malloc_stats_print<parameter/></function>, followed by a string
+ pointer. Please note that doing anything which tries to allocate memory in
+ this function is likely to result in a crash or deadlock.</para>
+
+ <para>All messages are prefixed by
+ “<computeroutput><jemalloc>: </computeroutput>”.</para>
+ </refsect1>
+ <refsect1 id="return_values">
+ <title>RETURN VALUES</title>
+ <refsect2>
+ <title>Standard API</title>
+ <para>The <function>malloc<parameter/></function> and
+ <function>calloc<parameter/></function> functions return a pointer to the
+ allocated memory if successful; otherwise a <constant>NULL</constant>
+ pointer is returned and <varname>errno</varname> is set to
+ <errorname>ENOMEM</errorname>.</para>
+
+ <para>The <function>posix_memalign<parameter/></function> function
+ returns the value 0 if successful; otherwise it returns an error value.
+ The <function>posix_memalign<parameter/></function> function will fail
+ if:
+ <variablelist>
+ <varlistentry>
+ <term><errorname>EINVAL</errorname></term>
+
+ <listitem><para>The <parameter>alignment</parameter> parameter is
+ not a power of 2 at least as large as
+ <code language="C">sizeof(<type>void *</type>)</code>.
+ </para></listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><errorname>ENOMEM</errorname></term>
+
+ <listitem><para>Memory allocation error.</para></listitem>
+ </varlistentry>
+ </variablelist>
+ </para>
+
+ <para>The <function>realloc<parameter/></function> function returns a
+ pointer, possibly identical to <parameter>ptr</parameter>, to the
+ allocated memory if successful; otherwise a <constant>NULL</constant>
+ pointer is returned, and <varname>errno</varname> is set to
+ <errorname>ENOMEM</errorname> if the error was the result of an
+ allocation failure. The <function>realloc<parameter/></function>
+ function always leaves the original buffer intact when an error occurs.
+ </para>
+
+ <para>The <function>free<parameter/></function> function returns no
+ value.</para>
+ </refsect2>
+ <refsect2>
+ <title>Non-standard API</title>
+ <para>The <function>malloc_usable_size<parameter/></function> function
+ returns the usable size of the allocation pointed to by
+ <parameter>ptr</parameter>. </para>
+
+ <para>The <function>mallctl<parameter/></function>,
+ <function>mallctlnametomib<parameter/></function>, and
+ <function>mallctlbymib<parameter/></function> functions return 0 on
+ success; otherwise they return an error value. The functions will fail
+ if:
+ <variablelist>
+ <varlistentry>
+ <term><errorname>EINVAL</errorname></term>
+
+ <listitem><para><parameter>newp</parameter> is not
+ <constant>NULL</constant>, and <parameter>newlen</parameter> is too
+ large or too small. Alternatively, <parameter>*oldlenp</parameter>
+ is too large or too small; in this case as much data as possible
+ are read despite the error.</para></listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><errorname>ENOMEM</errorname></term>
+
+ <listitem><para><parameter>*oldlenp</parameter> is too short to
+ hold the requested value.</para></listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><errorname>ENOENT</errorname></term>
+
+ <listitem><para><parameter>name</parameter> or
+ <parameter>mib</parameter> specifies an unknown/invalid
+ value.</para></listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><errorname>EPERM</errorname></term>
+
+ <listitem><para>Attempt to read or write void value, or attempt to
+ write read-only value.</para></listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><errorname>EAGAIN</errorname></term>
+
+ <listitem><para>A memory allocation failure
+ occurred.</para></listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><errorname>EFAULT</errorname></term>
+
+ <listitem><para>An interface with side effects failed in some way
+ not directly related to <function>mallctl*<parameter/></function>
+ read/write processing.</para></listitem>
+ </varlistentry>
+ </variablelist>
+ </para>
+ </refsect2>
+ <refsect2>
+ <title>Experimental API</title>
+ <para>The <function>allocm<parameter/></function>,
+ <function>rallocm<parameter/></function>,
+ <function>sallocm<parameter/></function>, and
+ <function>dallocm<parameter/></function> functions return
+ <constant>ALLOCM_SUCCESS</constant> on success; otherwise they return an
+ error value. The <function>allocm<parameter/></function> and
+ <function>rallocm<parameter/></function> functions will fail if:
+ <variablelist>
+ <varlistentry>
+ <term><errorname>ALLOCM_ERR_OOM</errorname></term>
+
+ <listitem><para>Out of memory. Insufficient contiguous memory was
+ available to service the allocation request. The
+ <function>allocm<parameter/></function> function additionally sets
+ <parameter>*ptr</parameter> to <constant>NULL</constant>, whereas
+ the <function>rallocm<parameter/></function> function leaves
+ <constant>*ptr</constant> unmodified.</para></listitem>
+ </varlistentry>
+ </variablelist>
+ The <function>rallocm<parameter/></function> function will also
+ fail if:
+ <variablelist>
+ <varlistentry>
+ <term><errorname>ALLOCM_ERR_NOT_MOVED</errorname></term>
+
+ <listitem><para><constant>ALLOCM_NO_MOVE</constant> was specified,
+ but the reallocation request could not be serviced without moving
+ the object.</para></listitem>
+ </varlistentry>
+ </variablelist>
+ </para>
+ </refsect2>
+ </refsect1>
+ <refsect1 id="environment">
+ <title>ENVIRONMENT</title>
+ <para>The following environment variable affects the execution of the
+ allocation functions:
+ <variablelist>
+ <varlistentry>
+ <term><envar>MALLOC_CONF</envar></term>
+
+ <listitem><para>If the environment variable
+ <envar>MALLOC_CONF</envar> is set, the characters it contains
+ will be interpreted as options.</para></listitem>
+ </varlistentry>
+ </variablelist>
+ </para>
+ </refsect1>
+ <refsect1 id="examples">
+ <title>EXAMPLES</title>
+ <para>To dump core whenever a problem occurs:
+ <screen>ln -s 'abort:true' /etc/malloc.conf</screen>
+ </para>
+ <para>To specify in the source a chunk size that is 16 MiB:
+ <programlisting language="C"><![CDATA[
+malloc_conf = "lg_chunk:24";]]></programlisting></para>
+ </refsect1>
+ <refsect1 id="see_also">
+ <title>SEE ALSO</title>
+ <para><citerefentry><refentrytitle>madvise</refentrytitle>
+ <manvolnum>2</manvolnum></citerefentry>,
+ <citerefentry><refentrytitle>mmap</refentrytitle>
+ <manvolnum>2</manvolnum></citerefentry>,
+ <citerefentry><refentrytitle>sbrk</refentrytitle>
+ <manvolnum>2</manvolnum></citerefentry>,
+ <citerefentry><refentrytitle>alloca</refentrytitle>
+ <manvolnum>3</manvolnum></citerefentry>,
+ <citerefentry><refentrytitle>atexit</refentrytitle>
+ <manvolnum>3</manvolnum></citerefentry>,
+ <citerefentry><refentrytitle>getpagesize</refentrytitle>
+ <manvolnum>3</manvolnum></citerefentry></para>
+ </refsect1>
+ <refsect1 id="standards">
+ <title>STANDARDS</title>
+ <para>The <function>malloc<parameter/></function>,
+ <function>calloc<parameter/></function>,
+ <function>realloc<parameter/></function>, and
+ <function>free<parameter/></function> functions conform to ISO/IEC
+ 9899:1990 (“ISO C90”).</para>
+
+ <para>The <function>posix_memalign<parameter/></function> function conforms
+ to IEEE Std 1003.1-2001 (“POSIX.1”).</para>
+ </refsect1>
+</refentry>
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